The process for producing man-made board products from cellulosic fibers, especially wood chips or other low-quality forest or wood residues, are well known to those skilled in the art. However, wood by-products are becoming increasingly more expensive and difficult to obtain as natural wood resources continually become more depleted, especially in third world countries and environments that are undesirable for producing wood. Furthermore, particle boards produced from such wood residues have been shown to be highly flammable. Thus, it has been desirable to replace the wood residues in the board production process with more easily obtainable agricultural waste products that are less expensive, less flammable, more abundant, and of the same or better quality than wood residue boards.
The concept of using waste agricultural products, such as straw, to build relatively permanent domiciles and other generally permanent buildings is well known. This concept includes replacing typical floors, wooden or metal stud walls, and ceilings and roof constructions normally used for on-site fabrication with panel boards made from agricultural fibers. The panel boards of this nature made in the past have had the structural and insulation properties of the conventional structures that they replaced.
Although the basic concept has been around for some time, various anomalies have prevented the commercial dominance of this concept over standard approaches. For instance, in the past, it has been difficult to manufacture such agricultural fiberboards that have a reliable and consistent density in the core of the fiberboard. In addition, the relatively high cost of manufacturing such a fiberboard was also a considerable problem.
Applicant resolved the problems of the past by inventing a method and apparatus for making compressed agricultural fiber structural board, as seen and disclosed in U.S. Pat. Nos. 5,945,132 and 6,143,220. Although the inventions described in the above-noted patents led to the creation of a relatively low-cost fiberboard having a core with a substantially consistent density, it was determined that certain inconsistencies and inefficiencies were leading to rather large variances in the quality and the cost of the fiberboard. For instance, the straw utilized to create the fiberboard contains various moisture levels depending on the type of straw and the time of year in which the straw is harvested. Since moisture is a key factor in the resulting density of the core of the fiberboard, the failure to control the moisture level in the straw prior to and during the fiberboard manufacturing process led to undesirable variances in the density of the core of the fiberboard. In addition, due to the structural integrity of straw, it is often difficult to provide a consistent amount of straw throughout the process once the straw is separated and cleaned. Failure to provide a consistent amount of straw throughout the process may lead to inconsistencies in the density of the fiberboard. These and other various processing factors led to certain inconsistencies and inefficiencies that were undesirable in a manufacturing environment.
Applicant further resolved the issues described above by disclosing a method for making a compressed structural fiberboard in U.S. Pat. No. 8,052,842. Although the method disclosed in the above-noted patent provided an improved method for making a compressed structural fiberboard over the previous methods, the disclosed process was still too inefficient to be competitive with other similar building materials in the building industry. For instance, the previous process for manufacturing compressed fiberboard was slow and required a high level of energy thereby leading to inefficiencies that increased the cost of manufacturing the compressed fiberboard. Also, the equipment and machinery used to produce the compressed fiberboard was large and heavy thereby requiring large amounts of factory floor space and reinforced foundations which added to the cost of manufacturing the compressed fiberboard. In addition, the process for producing the compressed structural fiberboard lacked sufficient industrial controls for monitoring and controlling the manufacturing process thereby leading to lower output rates and quality with higher levels of scrap rates. All of these factors led to inefficiencies that are undesirable in an industrial environment.
It is desirable to produce an efficient method and apparatus for producing a compressed structural fiberboard that can compete with similar building products in the building industry.